Film bulk acoustic resonator having supports and manufacturing method therefore

Abstract

A film bulk acoustic resonator (FBAR) has a support structure, a piezoelectric resonator, and a signal line that is electrically connected, e.g., through a via, to the piezoelectric resonator, all on a semiconductor substrate. Support(s) and/or the via mount the piezoelectric resonator at a predetermined distance from the semiconductor substrate, allowing an ideal shape of the resonator to be realized. The signal line may include a patterned inductor. A capacitor can be formed between the via and the signal line. The resonance characteristics can be enhanced since the substrate loss caused by the driving of the resonator can be prevented due to an air gap formed by the predetermined distance. The resonance frequency can be adjusted by altering the pattern of the inductor, the capacitance of the capacitor and/or the thickness of the piezoelectric layer, also allowing Impedance matching to be readily realized.

Description

BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates to an acoustic resonator and a manufacturing method therefore, and more particularly to a film bulk acoustic resonator using a piezoelectric material and a manufacturing method therefore. [0003] 2. Description of the Related Art [0004] Recently there have been dramatic developments in wireless mobile communication technologies. Such mobile communication technologies require diverse radio frequency (RF) parts that can efficiently transfer information in a limited frequency bandwidth. In particular, the filter of the RF parts is one of key element in mobile communication technologies. This filter serves to filter innumerable waves in air to allow users to select or transfer desired signals, thereby enabling high-quality communications. [0005] Currently, wireless communication RF filters are typically dielectric filters or surface acoustic wave (SAW) filters. A dielectric filter provides h...

AI Technical Summary

Benefits of technology

[0033] As aforementioned, the film bulk acoustic resonator and the manufacturing method therefore can reduce the substrate dielectric loss due to the resonance structure being spaced at a predetermined distance from the substrate. Further, impedance matching with external circuits can be easily realized. Finally, the integration with other devices can be improved, since passive and active devices, such as an inductor and / or a capacitor, can be integrated in the space between the substrate and the resonance structure.

Problems solved by technology

However, the dielectric filter cannot be sufficiently reduced in size and cannot be integrated with other integrated circuits (ICs), including the recently developed Monolithic Microwave Integration Circuit (MMIC).

However, a SAW filter's line width for the InterDigital Transducer (IDT) is limited to about 0.5 μm since the process for creating the SAW filter includes a light exposure using ultraviolet (UV) rays.

Accordingly, the SAW filter cannot cover the high frequency bands, e.g., over 5 GHz, and it is still difficult to construct the MMIC structure on a semiconductor substrate as a single chip.

However, the membrane-based FBAR occupies a large area due to the orientation of the silicon substrate, and is easily damaged due to the low structural stability upon a subsequent packaging process, resulting in low yield.

However, the Bragg reflector-based FBAR the thickness adjustments of the layers 22-24 for the total reflection are not easy and the manufacturing cost increases due to the formation of these reflection layers.

However, the manufacturing yield of the air gap-based FBAR is reduced since the structure is easily damaged due to exposing the structure for a long time while the sacrificial layer is removed.

Further, the manufacturing process of the air gap-based FBAR is complicated.

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